This work presents the relationship between the irradiance, in the city of Pasto, and the power generated by three types of PV panels: monocrystalline, polycrystalline and amorphous silicon thin film. The irradiance data was collected in the year 2014, using the weather station DAVIS Advantage PRO 2.0. The power generated by the PV panels was monitored and recorded using an acquisition system, in real time, developed by the authors. This information was stored into a MySQL database (manager free database), the information decoding process and graphical representation was automatic and daily registered with analysis software variables, developed by the authors with Visual Studio 2010. As a result of this work, a model that predicts the possible behaviour of the power generated by each one of the technologies concerning the irradiance was obtained; this methodology can be replicated and adjusted to the conditions of a place where a PV system based on one of three technologies could be placed, evaluating which one has a better efficiency. Specifically for the city of Pasto, the best result was got by monocrystalline silicon panels.